In the RA validation set, CXCL10 and CCL18 showed high expression difference, whereas DUOX2 showed no significant difference (Fig. 6I); CXCL10 and CCL18 expressed fair diagnostic efficiency (AUC > 0.7), whereas DUOX2 expressed poor discriminative efficiency (AUC < 0.7) (Fig. 6M). Here, CCL18 is linked to rheumatoid arthritis.